1. Field of the Invention
The present invention relates to a pad arrangement of a chip. More particularly, the present invention relates to a pad arrangement of a chip suitable for forming a wire-bonding connection.
2. Description of the Related Art
With the rapid advance in electronic technologies, electronic products with more personalized characteristics, more powerful functions, a lighter, slimmer and more compact body have been developed. Thus, the circuit design and structural design of the electronic products are increasingly complicated. In the packaging of integrated circuit chip, for example, the electrical connection between the chip and the carrier is achieved through wire bonding. Typically, one end of a conductive wire is connected to a pad on an active surface of the chip while the other end of the conductive wire is connected to the contact on the carrier. Because of some limitations in the wire-bonding technique, the pads are normally disposed in the peripheral region on the active surface of the chip.
FIG. 1 is a top view of a conventional chip structure suitable of wire bonding. FIG. 2 is an enlarged view of region A in FIG. 1. As shown in FIGS. 1 and 2, the chip structure 100 has a chip 110 and a plurality of pads 120. The pads 120 are disposed on an active surface 112 of the chip 110 extending along one side 112a of the active surface 112. The pads 120 include a plurality of signal pads 122 and a plurality of non-signal pads 124. The non-signal pads 124 can be power pads or ground pads. The signal pads 122 are arranged to be adjacent and parallel to the side 112a so that a plurality of signal pad rows is formed. The non-signal pads 124 are disposed between the side 112a and the signal pads 122 and parallel to the side 112a so that a non-signal pad row is formed.
With the gradual miniaturization of the chip 110, the distance d separating two adjacent pads 120 on the active surface 112 of the chip 110 is reduced. Therefore, as these pads 120 on the chip 110 are electrically connected to a carrier (not shown) through wire bonding, the distance between the signal wires (not shown) connected to two adjacent signal pad 122 is also reduced. When the distance separating two adjacent signal wires is too short, electromagnetic coupling between two signal wires will be intense. Under such condition, a signal traveling along one of the signal wires will lead to some unwanted cross talk with an adjacent signal wire and a lowering of signal transmission quality. In a high-frequency and high-speed transmission environment, the cross talk may lead to data reading errors and faults in operations.